The present invention relates to an apparatus and a method for detecting the presence of a substance or substances in or on a medium, more particularly to such apparatus and method wherein the substance or substances are hydrocarbonous (especially, petrochemical) in nature and the medium is water.
In recent times various forms of air and water pollution have damaged or threatened our world's environment and its lifeforms. Preservation of the earth's environment has become a major concern to its inhabitants.
Petrochemical (often referred to as "oil") spillage from off-shore drilling platforms, tankers and pipelines constitutes a rampant and insidious form of water pollution. Among the various approaches to monitoring oil spillage, perhaps the least efficient are those requiring direct human sensory (e.g., visual or olfactory) perception of the waters from land sites, aircraft or marine craft. Potentially more efficient is an approach which, rather than rely on human senses, automatically senses and signals the presence of hydrocarbonous matter in a given body of water.
Utilization of fiber optic technology for automatically detecting oil spillage is disclosed by Jacobson U.S. Pat. No. 5,208,465 and Luukkala et al. U.S. Pat. No. 4,882,499. Gergely U.S. Pat. No. 4,446,370 discloses automatic light detection of induced fluorescence in oil. These and other oil detection methodologies which analogously rely upon direct visual observation/sensing of the oil are rendered ineffective or less effective, however, in situations wherein the oil sought to be perceived does not appreciably deviate in appearance or color from that of the ambient water.
Hence, oil spillage detection approaches which are based on ocular principles may be limited or compromised by lack of visibility of the oil, for example due to darkness of night or to "blending in" of the oil with the surrounding water. On the other hand, as anyone having a normal sense of smell can attest, a hydrocarbonous liquid substance virtually always emits or evaporates a discernible hydrocarbonous gaseous substance, regardless of the visual circumstances.